1. Field of the Invention
The invention is directed to a driving calibration apparatus and a driving calibration method thereof. More particularly, the invention is directed to an apparatus for calibrating driving voltages of an electrostatic MEMS scanning mirror and a driving calibration method thereof
2. Description of Related Art
An MEMS scanning mirror is an important device for transmitting optical signals and is widely applied to optical-electro-mechanical system integrated products and techniques, such as projectors, barcode readers, optical modulators, optical choppers, optical switches, optical positioning, and so forth. The MEMS scanning mirror is composed of an actuator and a plane mirror, the actuator is in charge of applying a force on the plane mirror to enable the plane mirror to generate angular displacement so as to reflect an incident optical signal, and a transmission direction of the optical signal is determined according to the angular displacement of the plane mirror. Methods for driving the MEMS scanning mirror are typically classified into an electrostatic, an electromagnetic, a thermo and a piezoelectric methods. Among them, the electrostatic MEMS scanning mirror has advantages, such as greater driving force and better compliance in semiconductor manufacturing processes and thus, have high potential.
When being applied in biaxial scanning, the electrostatic MEMS scanning mirror controls swing angles by means of controlling DC voltages. Since the swing angles of the electrostatic MEMS scanning mirror is not linearly relative to the DC voltages, difficulties occur in controlling the swing angles of the electrostatic MEMS scanning mirror, and as a result, the electrostatic MEMS scanning mirror probably incurs an issue of non-uniform scanning intervals. More specifically, when being applied in image projection, the issue of non-uniform scanning intervals probably incurs an issue of non-uniform brightness of images projected by the electrostatic MEMS scanning mirror.